A thermoplastic elastomer (TPE) has both of excellent processing characteristics of plastic and characteristics of an elastomer. Specifically, in the TPEs, there are those which form a copolymer by chemical bonding of a hard segment and a soft segment in a polymer and those which blend a hard polymer and a soft polymer to form a sea-island structure. Since the hard segment plays a role of a pseudo-crosslinking point (being not a covalent bond), elasticity like rubber is exhibited. The hard segment is melt at high temperature to lose the function of the crosslinking point so that it undergoes plastic deformation and thus can flow.
Examples of the TPEs include olefin-based, styrene-based, polyester-based, polyurethane-based, polyamide-based, and fluorine-based TPEs, according to the type of a polymer that constitutes the TPE.
Of them, a polyurethane-based elastomer (TPU) is excellent in flexibility, bending resistance, and mechanical strength, and thus the TPU is used for various use applications for automobiles, civil engineering and construction, electric and electronic equipment, and sports equipment.
In order to improve the physical property of the TPU, for example, elongation, a relatively low-molecular weight phthalate ester-based plasticizer is used. However, when the plasticizer is used, problems of decreased strength of the TPU, bleeding out of the plasticizer due to the long-term use thereof, decreased wear resistance, and the like occur and thus, depending on the use application, the use of the plasticizer affects adversely in some cases.
A polyrotaxane has properties that, when a cyclic molecule constituting the polyrotaxane moves on the linear molecule, viscoelasticity, low compression permanent strain, and the like occur in a crosslinked body of polyrotaxanes, a crosslinked body of a polyrotaxane and a polymer other than the polyrotaxane, and the like. For this reason, the polyrotaxane is expected to be applied to various use applications, and thus, research and development thereof have been actively conducted.
For example, Patent Document 1 discloses a photocrosslinkable polyrotaxane, wherein a cyclic molecule of a polyrotaxane has a photopolymerizable group at side chain terminals of a lactone or carbonate polymer, a cured product formed by using the polyrotaxane, and the like. In addition, it is disclosed that the cured product has properties such as scratch resistance, folding resistance, and low hysteresis loss.
However, the cured product disclosed in Patent Document 1 is a thermosetting, and thus Patent Document 1 does not disclose nor suggest a thermoplastic polymer, in particular, a thermoplastic elastomer.